diatom

[ dahy-uh-tuh m, -tom ]
/ ˈdaɪ ə təm, -ˌtɒm /

noun

any of numerous microscopic, unicellular, marine or freshwater algae of the phylum Chrysophyta, having cell walls containing silica.

Origin of diatom

1835–45; < New Latin Diatoma originally a genus name, feminine noun based on Greek diátomos cut in two. See dia-, -tome
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British Dictionary definitions for diatom

diatom
/ (ˈdaɪətəm, -ˌtɒm) /

noun

any microscopic unicellular alga of the phylum Bacillariophyta, occurring in marine or fresh water singly or in colonies, each cell having a cell wall made of two halves and impregnated with silicaSee also diatomite

Word Origin for diatom

C19: from New Latin Diatoma (genus name), from Greek diatomos cut in two, from diatemnein to cut through, from dia- + temnein to cut
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for diatom

diatom
[ dīə-tŏm′ ]

Any of various one-celled aquatic organisms of the class Bacillariophyceae that have hard bivalve shells (called frustules) composed mostly of silica, can perform photosynthesis, and often live in colonies. They make up a large portion of the marine plankton and are an important food source for many aquatic animals. The skeletal remains of diatoms are the main constituent of diatomite.
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